Method for creating a double bundle ligament orientation in a single bone tunnel during knee ligament reconstruction

ABSTRACT

A method and construct for joint repair in which attachment of a double bundle graft ligament approximates anatomic orientation using interference fixation in a single bone tunnel. The double bundle graft features separable strands. A threaded screw is inserted between the separable strands and provides interference fixation of the graft against radially opposing walls defining the bone tunnel. Attachment of the graft using separated strands more closely approximate the configuration of the native ligament. The resulting reconstruction exhibits mechanical functionality that more accurately mimics that of the intact joint, with a minimum of associated tissue morbidity.

This a application claims the benefit of U.S. Provisional ApplicationSer. No. 60/515,429, filed Oct. 30, 2003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to cruciate ligament reconstruction, andmore specifically to anatomically accurate cruciate ligamentreconstruction using double-bundle ligament grafts in single bonetunnels.

2. Description of the Related Art

Cruciate ligament reconstruction is routinely performed by creatingfemoral and tibial tunnels, and various graft types are used to replacethe native cruciate ligament. Most reconstructions are performed using asingle-bundle ligament graft made of autograft or allograft material.

Biomechanical studies have shown that an anatomic double-bundle cruciateligament reconstruction can be superior in restoring normal knee laxitycompared with conventional single-bundle isometric reconstructions.Double-bundle reconstructions, as compared to single-bundlereconstructions, more closely approximate the structure andconfiguration of the native tendon, and better accommodate the knee's“screw-home” mechanism.

Double-bundle reconstructions currently involve individual fixation foreach strand of the graft. The need to individually fixate each strand ofthe double-bundle graft adds to the complexity and cost of theprocedure. Double-bundle reconstructions also are performed as shown inU.S. Pat. No. 6,623,524 to Schmieding, the disclosure of which isincorporated herein by reference. Methods for repairing torn cruciateligaments using double-bundle grafts that are simpler to complete andmore closely approximate the native ligament development would enhancereconstruction results.

SUMMARY OF THE INVENTION

The present invention provides methods and apparatus for fixing a doublebundle ligament in single bone tunnels during knee ligamentreconstruction. The techniques produce a more anatomically correctligament reconstruction, particularly as in the case of the anteromedialand posterolateral bundles of the anterior cruciate ligament (ACL).

In order to reestablish native anatomical biomechanics of the damagedligament, the fixation method of the present invention provides a doublebundle configuration of the ligament using a single tunnel at each ofthe femoral and tibial attachment sites.

A double, triple, or quadruple graft is prepared, and a femoral socketand a tibial tunnel, in the form of axially elongate openings, arecreated for ligament reconstruction in the standard fashion. Referenceis made to examples of standard ligament reconstruction techniquesdisclosed in U.S. Pat. No. 5,320,626 to Schmieding and U.S. Pat. No.5,350,383 to Schmieding et al., the disclosures of which areincorporated herein by reference.

A notcher, burr or rasp is used to remove material from the tunnel wallsto notch or widen the tunnel openings. The notches accommodate graftstrands that are forced against the tunnel walls and into the notches bya fixation implant inserted between strands of the replacement graft, asdescribed further below.

The notches are oriented such that strands of a ligament graft fixed inthe tunnel achieve an orientation that more closely approximates that ofthe native ligament bundles. A fixation implant installed betweenstrands of the graft spread the strands to approximate the anatomicalattachment and functionality of the ligament being replaced. In apreferred embodiment, fixation is achieved using an interferenceimplant, preferably in the form of a threaded screw. The techniqueprovides simultaneous anatomical spreading and fixation in each tunnel.

An exemplary application of the technique to reconstruction of theanterior cruciate ligament in the human knee features positioning athreaded interference screw between the anteromedial and posterolateralbundles of the ACL in each of the pre-formed tibial tunnel and femoralsocket. Installation of the tibial and femoral screws preferably is madein a retrograde fashion, reference being made to examples of retrogradeinterference fixation described in U.S. Pat. No. 6,461,373 to Wyman etal., the disclosure of which is incorporated herein by reference.

The reconstruction techniques according to the present invention providea more anatomical reconstruction that maximizes graft stiffness withtrue joint line fixation, which reduces tunnel widening. In addition,with respect to knee reconstructions, the techniques substantiallyincrease femoral and tibial graft fixation strength compared to standardinterference screws. Further, the invention maintains graft tensionduring tibial screw fixation, and replaces the need for double tunnelsurgery using reproducible transtibial techniques and instrumentation.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the invention will be gained byreference to the descriptions below when read in conjunction with theattached drawings listed as follows:

FIG. 1 illustrates a graft ligament used in an exemplary method ofanterior cruciate ligament reconstruction according to the presentinvention;

FIG. 2 is a schematic anterior view of a human left knee shown during astep of notch formation in femoral and tibial tunnels in the method ofanterior cruciate ligament reconstruction according an exemplaryembodiment of the present invention;

FIG. 3 illustrates the left knee with a ligament graft passed into thetunnels in preparation for femoral fixation in retrograde fashionaccording to the present invention;

FIG. 4 illustrates alignment of a femoral retroscrew in the knee in afurther step of the reconstruction method according to the presentinvention;

FIG. 5 illustrates positioning of the femoral retroscrew with respect tothe graft strands in the method of ligament reconstruction according tothe present invention;

FIG. 6 illustrates insertion of the femoral retroscrew according to thepresent invention;

FIG. 7 illustrates the knee in preparation for insertion of a tibialretroscrew according to the present invention;

FIG. 8 illustrates a step of delivering the tibial retroscrew into theknee joint according to the present invention;

FIG. 9 illustrates alignment of the tibial retroscrew with the tibialtunnel according to the present invention;

FIG. 10 illustrates insertion of the tibial retroscrew in the tibialtunnel according to the present invention;

FIG. 11 illustrates a further step of the exemplary ligamentreconstruction method according to the present invention; and

FIG. 12 illustrates secondary screw fixation in the exemplary ligamentreconstruction method according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

An exemplary method of anterior cruciate ligament (ACL) reconstructionin a human knee according to the present invention is described below inconjunction with FIGS. 1-12. The teachings, methods, and techniquespresented can be applied as well to other surgical applications,including without limitation posterior cruciate ligament (PCL)reconstruction in the human knee, for example, as well asreconstructions of other ligaments and joints in humans and skeletalcreatures. Adaptations and adjustments to the exemplary technique ofhuman ACL reconstruction described undoubtedly will be necessary in theother surgical applications. They will be well within the skill of thepractitioner capable of understanding and undertaking the presentteachings and techniques, however, and readily accomplished withoutundue experimentation.

Referring initially to FIG. 1, a double hamstring autograft or tibialistendon allograft 2 of a minimum length of 140 mm is preferred for thedouble bundle ACL technique. A midline 4 is marked and 20 mmwhip-stitches 6, 8 of #2 FiberWire™ suture is placed on each side of thegraft mid line 4. (FiberWire™ suture is sold by Arthrex, Inc. of Naples,Fla., the assignee of the present application, and is described andclaimed in U.S. Pat. No. 6,716,234, the disclosure of which isincorporated herein by reference). Suturing across the midline 4 isavoided to allow for folding of the graft during tunnel insertion,described in more detail below. Another pair of 20 mm whip-stitches 10,12 is placed 50 mm from the proximal ends of the graft 2 to enhancetibial RetroScrew fixation, described further below. A #5 FiberWire™graft passing suture 14 is looped around the midline 4. Sutures 16, 18are secured with whip-stitching to the ends of graft 2.

Referring to FIG. 2, a skeletal knee joint 20 is illustrated showingterminal portions of a femur 22 with femoral condyles 24 engaging medialand lateral menisci 26, 28 of a tibia 30. A portion of a fibula 32 alsois shown. Femoral socket 34 and tibial tunnel 36 are prepared instandard transtibial fashion. Femoral socket orifice 38 is notched atthe 10:00 (40) and 4:00 (42) positions for left knee 20, to accommodateanteromedial and posterolateral bundles of graft 2, described below infurther detail. The anterior and posterior tibial tunnel orifices arenotched using a 5 mm wide Retro Tunnel notcher 44, sold by Arthrex, Inc.of Naples, Fla.

Referring to FIG. 3, graft 2, folded at the midline 4. is passed intothe femoral socket 40. A #2 FiberStick™ 46 (FiberStick™ is a length ofFiberWire™ with a stiffened tip, disclosed in U.S. Patent ApplicationPublication No. US 2003/0153948, incorporated herein by reference) ispreloaded in a RetroScrew driver 48 with a 2 cm length extending fromthe tip of driver 48. The driver 48 is inserted through the tibialtunnel 36 anterior the graft 2. The extended end of FiberWire™ 46 isretrieved and pulled out an anteromedial portal. The FiberStick™ 46 isinserted to a head of a femoral retroscrew 50. The FiberStick™ 46 isknotted at the tip of the Femoral RetroScrew 50 with at least three halfhitches. The Femoral RetroScrew 50 is then snapped into the end of aShoehorn Cannula 52, sold by Arthrex, Inc. of Naples, Fla. The cannula52 is inserted into the anteromedial portal and a cannula obturator (notshown) is used to push the screw 50 into the joint.

Referring to FIG. 4, the retroscrew 50 is urged by drawing on FiberStick46 until the RetroScrew 50 is in axial alignment with tibial tunnel 36.The Femoral RetroScrew 50 is then mounted on the tip of driver 48, carebeing taken to remove soft tissue from the driver/screw interface priorto seating the screw 50. The RetroScrew 50 is fully inserted onto thedriver when a laser line 54 is flush with the head of the screw. TheFiberStick™ suture 46 is removed out the anteromedial portal.

Referring next to FIG. 5, graft 2 is pulled distally to visualize thewhip-stitching 6, 8 and to position the Femoral RetroScrew 50 betweenthe two strands of the folded graft 2. The graft 2 is pulled slowly sothat it is seated fully in the femoral socket 40 while advancing thescrew 50 into the femoral socket 40 between the graft strands. A probe(not shown) may be used to orient the two bundles of graft 2anatomically into the respective notches of femoral tunnel 40. Thedistal end of the whip-stitching 6, 8 should be flush with the openingof tunnel 40 prior to insertion of screw 50.

The graft 2 is tensioned in the femoral socket 40, and graft strands arepositioned into the notches of the femoral tunnel 40. The FemoralRetroScrew 50, is positioned between the graft strands and axiallyaligned with the tunnel 40 in 90° of knee flexion. The diameter offemoral RetroScrew 50 should be equal to or 1 mm larger than thediameter of the drilled femoral socket. The femoral RetroScrew 50separates the folded graft 2 into two anatomical bundles. Theconcentrically-positioned screw 50, under the looped graft 2,substantially increases femoral pull-out strength of the graft 2 ascompared to prior techniques.

Referring to FIG. 7, the knee is cycled and the driver 48 is reloadedwith a #2 FiberStick™ 56 and reinserted up the tibial tunnel 36 anteriorto the graft 2. The proximal end of the FiberStick™ 56 is retrieved andpulled out the anteromedial portal using a grasper 58.

Referring to FIG. 8, the end of FiberStick™ 56 is passed through the tipof a Tibial RetroScrew 60 having a diameter appropriate to the tibialtunnel diameter. A Mulberry knot is tied behind the round head of theretroscrew 60. The Tibial RetroScrew 60 is snapped into the end of theShoehorn Cannula 52 and the cannula 52 inserted into the anteromedialportal. A cannula obturator is used to push the retroscrew 60 into thejoint.

Referring to FIG. 9, the knee is cycled and the driver 48 is reloadedwith a #2 FiberStick™ 62 and reinserted up the tibial tunnel 36 anteriorto the graft 2. The Tibial RetroScrew 60 is mounted onto the tip ofdriver 48 by pulling on the FiberStick™ suture 62. Soft tissue isremoved from the screw/driver interface prior to seating of the screw60. The screw 60 is fully inserted on the driver 48 when a laser line onthe driver 48 is flush with the tip of the screw. The FiberStick™ 62 iswrapped around handle posts on the driver 48 (FIG. 10) to secure thescrew 60 for retrograde insertion.

While fully tensioning the graft 2 in approximately 20° of knee flexion,the Tibial RetroScrew 60 is inserted counter-clockwise, anterior to thegraft 2 under full visual control. Insertion is completed when the roundhead of the screw 2 is slightly countersunk with respect to the tibialtunnel orifice. The FiberWire™ 62 is released from the driver handle andwithdrawn out the anteromedial portal by pulling from the knotted endusing a grasper 58, as shown in FIG. 11.

Secondary screw fixation of the graft in the tibial tunnel may beperformed by inserting a second Femoral RetroScrew 64 into the distalend of the tibial tunnel 36 (in an antegrade fashion). Such bi-corticalfixation of the graft 2 in the tibial tunnel 36 provides maximum graftfixation strength, creates a blood-rich healing environment in thetunnel 36 between the two screws 60, 64, and reduces post-op soft tissuehematoma.

Although the present invention has been described in connection withpreferred embodiments, many modifications and variations will becomeapparent to those skilled in the art.

1. A method of surgical ligament repair comprising: forming a tibialtunnel and a femoral tunnel, each tunnel having tunnel walls; wideningthe tibial and femoral tunnels by removing bone material from the tunnelwalls to form tibial and femoral tunnels that are wider in one radialdirection than another; and securing a double bundle ligament graft inthe widened tibial and femoral tunnels.
 2. A method as in claim 1,wherein the step of securing the double bundle ligament graft includessecuring the graft in the tunnels by interference fixation.
 3. A methodas in claim 2, wherein the double bundle ligament graft includes atleast two strands, and the double bundle ligament graft is secured byinstalling a respective implant between two strands of the graft suchthat the graft strands are secured separately between an outer wall ofthe respective implant and the tunnel walls.
 4. A method as in claim 3,wherein the direction in which the tunnels are widened and theorientation in which the graft strands are secured within the tunnelsapproximates the anatomical orientation of a native ligament beingreplaced.
 5. A method of graft fixation comprising: removing bone toforming an axially-elongated opening; inserting a ligament graft intothe opening, the ligament graft having at least two separable strands;and installing a fixation device between the strands of the graft.
 6. Amethod according to claim 5, wherein the step of removing bone comprisesremoving bone material so as to develop an oval cross-section in theopening.
 7. A method according to claim 5, wherein the opening is atunnel.
 8. A method according to claim 7, wherein the fixation device isinstalled in a retrograde fashion by drawing the fixation device intothe tunnel.
 9. A method according to claim 8, comprising drawing thefixation device from an internal end opening of the tunnel toward anexternal end opening of the tunnel.
 10. A method according to claim 5,wherein the opening is a socket.
 11. A method according to claim 5,wherein the fixation device comprises a threaded screw, and the step ofinstalling the fixation device comprises rotated driving of the threadedscrew to achieve interference fixation.
 12. A construct comprising: afirst elongate opening formed in a first bone; a first fixation device;and a graft having at least two separable strands, the first fixationdevice installed between the at least two separable strands to secure tothe graft to bone walls defining the first elongate opening.
 13. Aconstruct according to claim 12, wherein the first elongate opening hasa cross-section that is wider in one direction than in another.
 14. Aconstruct according to claim 13, wherein the first elongate opening hasa cross-section that oval in shape.
 15. A construct according to claim13, wherein the first fixation device comprises a threaded screw.
 16. Aconstruct according to claim 12, further comprising a second elongateopening formed in a second bone and a second fixation device installedbetween the at least two separable strands to secure to the graft tobone walls defining the second elongate opening.
 17. A constructaccording to claim 16, wherein the first bone is a femur and the secondbone is a tibia.
 18. A construct according to claim 16, wherein thesecond fixation device comprises a threaded screw.